1. Field of the Invention
The present invention relates to an exhaust gas recirculation (EGR) system. More particularly, the present invention relates to an EGR system for preventing condensed water from exhaust gas from inflowing to an EGR valve.
2. Description of the Related Art
Generally, an EGR system reduces nitrogen oxides in exhaust gas. A conventional EGR system includes an exhaust gas passage mounted to a cylinder head and an EGR valve disposed at an exhaust manifold or the exhaust gas passage. The EGR valve opens/closes the exhaust gas passage to selectively transmit exhaust gas to a combustion chamber.
However, condensed water from the exhaust gas inflows to the EGR valve after the engine stops. If condensed water inflows to the EGR valve in winter, the EGR valve does not operate or freezes up. Furthermore, if a vehicle is parked for a long time, because corrosion occurs in the EGR valve due to the condensed water, malfunction of the EGR valve may occur.
In addition, if the EGR valve does not operate due to being frozen, fuel consumption and exhaust gas characteristics are deteriorated when the vehicle starts.
The above information disclosed in this background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.